3D printer filament types explained: PLA vs PETG vs ABS vs TPU

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Filament is the plastic an FDM printer melts to build your part, and the material you choose affects strength, flexibility, heat resistance, fumes and how hard the print is to get right. Here is a plain-language guide to the four you will meet first, plus the habit that saves more prints than any setting: keeping filament dry.

A rule before the details

Every spool should carry a recommended nozzle temperature range and often a bed temperature from its maker. Start with the maker's figures, not someone else's, because the same plastic varies between manufacturers and even between colours. Print a temperature tower (a small test model that steps through temperatures) when you open a new type of filament, and pick the band that looks best.

PLA: the beginner's material

Why people use it: easy to print, low warping, little smell, and a wide range of colours and finishes.
Strengths: stiff and precise, good surface detail, fine for models, prototypes, organisers and decorative pieces.
Weaknesses: softens at fairly low temperatures, so it can deform in a hot car or near a heater. It is also more brittle than the others and can snap rather than bend.
Printing: an open-frame printer is fine; a part-cooling fan helps detail.

PETG: the practical all-rounder

Why people use it: tougher and more heat-resistant than PLA, with some flex before it breaks.
Good for: functional parts, brackets, outdoor-ish items, containers.
Weaknesses: prone to stringing (thin wisps between parts) and can stick too well to some smooth build surfaces. Many people use a release agent or a textured plate.
Printing: usually hotter than PLA, with less cooling. Slow down a little if you see blobs.

ABS (and its cousin ASA)

Why people use it: good heat resistance and toughness, and it can be sanded and smoothed. ASA is similar with better resistance to sunlight.
Weaknesses: it shrinks as it cools, so it warps and cracks between layers unless the surrounding air stays warm. It also gives off noticeable fumes.
Printing: an enclosure is close to essential, along with a heated bed and good ventilation or filtration. It is not a good first material.

TPU: flexible filament

Why people use it: rubbery and impact-absorbing. Think phone cases, gaskets, bumpers, feet for furniture.
Weaknesses: it can buckle in the extruder because it is soft, especially on printers where the motor is far from the nozzle.
Printing: slow is the key word. Reduce speed, and reduce or disable retraction to avoid jams. Harder grades are easier to print than very soft ones.

Keeping filament dry

Most filaments absorb moisture from the air, some faster than others; PETG, TPU and nylon are well known for it. Wet filament causes:

popping or hissing at the nozzle
rough, bubbly surfaces and extra stringing
weaker parts, because steam leaves tiny voids

How to prevent and fix it:

Keep spools you are not using in a sealed bag or box with desiccant.
Close the bag again as soon as you finish printing.
If a spool has gone wet, dry it in a dedicated filament dryer at the temperature its maker suggests. Do not guess with a kitchen oven: oven thermostats can overshoot and soften the spool or the filament itself.
For long prints with hygroscopic materials, feed straight from a dry box.

Which one should you buy first?

Start with a spool of PLA from a maker that prints its temperature range on the label. Add PETG once you want stronger parts, then TPU or ABS when you have a specific need and, for ABS, an enclosure and ventilation. Which filament gave you the most trouble, and what fixed it? Ask questions or share your settings in the comments.